QuarterlyNational Accounts (QNA) data play a vital role in developing and monitoring sound economic and financial programs. The recent financial crises taught us that availability of timely key high-frequency data is critical for detecting sources of vulnerability and implementing corrective measures in time. This Manual has been drafted to help countries establish or strengthen quarterly national accounts that meet users needs. It has been designed for compilers who have a knowledge of national accounting concepts and methods in an annual context and are in the process of introducing or improving a QNA system. As well, the Manual should be of interest to sophisticated QNA users. The Manual is a direct result of material prepared for training seminars and technical assistance in support of the Special Data Dissemination Standard, and it has benefited from comments from country experts during these seminars and during an expert group meeting in June 2000, in which country experts and experts from other international organizations participated. It takes its place alongside the other manuals prepared or being prepared in the IMF's Statistics Department, and, like these other manuals, it is fully consistent with the System of National Accounts 1993.